Quinolinic acid is a compound that is widely used as an intermediate for medicines, dyes, agricultural pesticides, and the like. In general, quinolinic acid is chemically prepared from a starting material such as quinoline, 2,3-dimethylpyridine, or 8-hydroxyquinoline obtained in petrochemical processes. For example, a chemical synthesis method of quinolinic acid includes obtaining a copper salt of quinolinic acid from a sulfate such as copper sulfate; and removing copper ions from the copper salt in a form of copper oxide precipitate. In such a synthesis method of quinolinic acid, the additional process of removing copper from copper salt of quinolinic acid may lead to generation of a large amount of byproducts and a low yield. The synthesis method may also result in a large amount of impurities, and thus, it may also be difficult to obtain quinolinic acid with a high yield with the synthesis method, even by recirculating a mother solution resulting from separation of crystals of quinolinic acid.
In recent times, there has been research into methods of producing quinolinic acid through a fermentation process. Producing quinolinic acid through a fermentation process is simple and results in a small amount of byproducts. However, a fermentation solution resulting from the fermentation process may include, in general, a low concentration of quinolinic acid, which is present as a combination with a salt.
Therefore, there is a need for an economical refining method for obtaining high-purity quinolinic acid crystals from the fermentation solution with a high recovery rate and low costs.